Montroydite

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Montroydite
Montroydite-mf17c.jpg
Vein of dark red montroydite and orange kleinite in a matrix of white calcite
General
CategoryOxide mineral
Formula
(repeating unit)
HgO
Strunz classification4.AC.15
Crystal systemOrthorhombic
Crystal classDipyramidal - mmm (2/m 2/m 2/m)
Unit cella = 5.52 Å, b = 6.6 Å, c = 3.52 Å; Z=4
Identification
ColorDeep red, brownish red to brown
Crystal habitLong prismatic, equant, rarely flattened; striated; massive to vermicular clusters
CleavagePerfect {010}
TenacitySectile
Mohs scale hardness1.5 - 2.0
LusterSub-adamantine, vitreous
StreakYellow brown
DiaphaneityTransparent to translucent
Specific gravity11.23
Optical propertiesBiaxial (+)
Refractive indexnα = 2.370 nβ = 2.500 nγ = 2.650
Birefringenceδ = 0.280
PleochroismDeep red-orange to yellowish brown (visible in thick sections)
2V angleLarge
References[1][2]

Montroydite is the mineral form of mercury(II) oxide with formula HgO. It is a rare mercury mineral. It was first described for an occurrence in the mercury deposit at Terlingua, Texas and named for Montroyd Sharp who was an owner of the deposit.[1]

Montroydite occurs in mercury deposits of hydrothermal origin. Associated minerals include: native mercury, cinnabar, metacinnabar, calomel, eglestonite, terlinguaite, mosesite, kleinite, edgarbaileyite, gypsum, calcite and dolomite.[2]

References[edit]